How do we determine the correct ID for inviting new hires to ensure they are added to the full series, does appending new attendees send notifications properly, and what is the significance of seriesMasterId in managing the attendee list for recurring

Question

For context:

We are using MS Graph to invite new hires to a recurring meeting series. We understand that we need to get existing attendees and add them to a list, then add the new hire to the list and send invite.

• What is the best method for sending one invite containing all preexisting attendees and the newly added hires. (C#)
• If we need to replicate this for each year's series, how do we know which ID to use to invite people so they are added to the full series after their date of hire?
• Does appending new people to the list of attendees for a series send an email notification to everyone, and does the invitee get one invite for the full series? (I believe you proved this isn't the case last week, I just want to be sure and make sure we have it documented)
• What is the role and significance of seriesMasterId in the context of adding attendees to a recurring event series?
• Should seriesMasterId always have a non-null value, and how does it affect adding or modifying attendees in a series?
• Are there any limitations in the MS Graph API for the maximum number of attendees that can be invited to a series event?